In a typical cellular radio system, mobile stations (also referred to as user equipment unit nodes, UEs, and/or wireless terminals) communicate via a radio access network (RAN) with one or more core networks. The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a base station subsystem (also referred to as a radio base station, base station, RAN node, a “NodeB”, and/or enhanced NodeB “eNodeB”). A cell area is a geographical area where radio coverage is provided by the base station subsystem equipment at a base station subsystem site. The base station subsystems communicate through wireless radio communication channels with mobile stations within range of the base station subsystems.
A mobile station communicating with a base station subsystem transmits an access request over a random access channel when the mobile station has data for transmission to the base station subsystem, and responsive to the access request, the base station subsystem transmits an assignment message identifying uplink resources that have been allocated for the mobile station uplink data transmission(s). The base station subsystem, however, may not respond to a first access request transmitted by the mobile station, for example, in the following situations: (1) if there is a collision (i.e., interference) with another access request transmitted by another mobile station at the same time so that the first access request is not received by the base station subsystem; (2) if the mobile station is a relatively low priority mobile station so that the first access request is ignored in favor of requests from higher priority mobile stations; and (3) if the base station subsystem has insufficient resources to respond to all access requests (e.g., during a period of high traffic). Accordingly, a mobile station may need to transmit a number of access requests separated in time by respective retransmission intervals before receiving an assignment message identifying uplink resources for the uplink data transmission(s).
In situations where the mobile station transmits multiple access requests separated by retransmission intervals before receiving an assignment message, the mobile station is required to look (e.g., monitor or search) for an assignment message from the base station subsystem during the retransmission intervals between transmitting the multiple access requests. These extended monitoring periods over the retransmission intervals may result in consumption of processing resources at the mobile station, consumption of power at the mobile station, and/or reduction of mobile station battery life.